Our invention is directed to (i) an emulsifier-free, single phase, nonporous, continuous, permeable polymeric film having a substantially uniform thickness, having entrapped and dissolved therein a fragrance material which is capable of evolving from the film into the environment proximate the film by means of molecular diffusion in a sustained and controlled release manner, as well as a process for using such polymeric film in order to impart a fragrance into the environment above the unobstructed outer surface of the film.
Controlled release fragrance compositions traditionally required prepackaging of encapsulated fragrances into the final product, for example, a coacervation, encapsulation system composed of fragrance encapsulated in a gelatin-gum arabic shell.
Control release systems using film forming polymers have been previously attempted. Thus, Japanese Published Patent Application J9 0057-428 abstracted as follows:
NIEK. D23 87-183168/26=J9 0057-428-B Prepn. of long-lasting fragrancexe2x80x94contg. hydroxypropyl:cellulose, ethanol and/or methanol soln. and vinyl pyrrolidone
NIPPON EKISHO KK 13.11.85-JP-252894 A97+P34 (Apr. 12, 1990) *J62114909-A A61k-07/46+A61l-09/01 13.11.85 as 252894 (RP) 1-30 wt % of hydroxypropylcellulose is added to the ethanol or methanol soln. of 1-60 wt % polyvinyl pyrrolidone. Then 1-60 wt % of fragrance material is added and mixed.
ADVANTAGExe2x80x94Long lasting fragrance is obtd. when applied to the film or paper. Polyvinyl pyrrolidone covers the fragrance material contained and prevents its loss. (J62114909-A) (3pp)
indicates that a long lasting fragrance is obtained when hydroxypropyl cellulose in an amount of from about 1 up to about 30% is added to ethanol or methanol previously containing polyvinylpyrrolidone in an amount of from about 1 up to about 60%. Then a fragrance material in an amount of from about 1 up to about 60% by weight is added to the resulting material and admixed. The resulting product is applied to a film or paper. The Japanese Published Application J9 0057-428 does not disclose a control release technology provided by our invention. The Published Japanese Application, furthermore, does not teach that an effective control release system requires that the fragrance element and the film forming polymer be chosen such that the film forming polymer permits the fragrance to molecularly diffuse into the environment surrounding the film at a permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-minute in a sustained and control release manner.
Holzner, U.S. Pat. No. 4,803,195 issued on Feb. 7, 1989 discloses personal care compositions having deodorant or antiperspirant activity and containing in addition to an active deodorant or antiperspirant base, a perfuming base either in the form of an aqueous emulsion or in microecapsulated form. The perfume base of Holzner is combined with a film forming substrate and an emulsifying agent. The Holzner, U.S. Pat. No. 4,803,195 claims:
xe2x80x9c1. A perfuming composition with deodorant or antiperspirant action for use in personal care, characterised in that it contains, in addition to an active deodorant or antiperspirant base, a perfuming base, either in the form of an aqueous emulsion, or in microencapsulated form, the said perfuming base being combined with
a. a solid film-forming substrate chosen from polyvinyl acetate, polyvinyl alcohol, dextrins, natural or modified starch, vegetable gums, pectins, xanthans, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose and lipoheteropolysaccharides, and
b. an emulsifying agent chosen from mono- or diglycerides of fatty acids, esters derived from the combination of fatty acids with sorbitol or a saccharide, or their alkoxylated derivatives, or an ester of tartaric, citric, ascorbic or lactic acid.xe2x80x9d
Holzner and Moulin, Canadian Patent No. 2,008,556, disclose a perfuming composition with deodorant or antiperspirant action for use in personal care compositions. The Holzner composition contains, in addition to an active deodorant or antiperspirant base, a perfuming base either in the form of an aqueous emulsion or in microencapsulated form, with the perfuming base being combined with a film-forming substrate and an emulsifying agent, and the composition being characterized in that the film-forming substrate contains polyvinylpyrrolidone. The film-forming substrate in the Holzner and Moulin patent can contain, other than polyvinylpyrrolidone, at least one compound chosen from polyvinyl acetate, polyvinyl alcohol, dextrins, natural or modified starch, vegetable gums, pectins, xanthanes, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and lipoheteropolysaccharides.
The prior art teaches away from our invention. Holzner, U.S. Pat. No. 4,803,195 requires the presence of an emulsifying agent and the formation of a fragrance polymer emulsion that is subsequently spray dried or used in emulsion form. Our invention does not require an emulsion, is applicable to all products containing volatile solvents that are applied to surfaces and requires that the film forming polymer is an effective xe2x80x9cbarrierxe2x80x9d to the fragrance or fragrance ingredient as determined by the xe2x80x9cFRAGRANCE PERMEATION TESTxe2x80x9d hereinafter defined and hereinafter described.
Thus, whereas the prior art discloses the usefulness of films formed from modified starches such as hydroxypropyl cellulose in conjunction with fragrance, films formed from modified starches such as hydroxy cellulose do not fall within the scope of our invention. Ethyl tiglate is a common fragrance ingredient and permeates through a film formed from hydroxypropyl cellulose at a rate equal to its evaporation rate as determined by the xe2x80x9cFRAGRANCE PERMEATION TESTxe2x80x9d described, infra. Thus, hydroxypropyl cellulose would not evolve from such film into the environment proximate to the film by means of molecular diffusion at a permeation rate of  less than 0.1 mg-mm/cm2-min.
Israel Patent No. 91422 issued on Oct. 31, 1995 (assigned to Dento-Med Industries Inc.) discloses a stable oil-in-water emulsion characterized in that it contains 2-hydroxyethyl methacrylate homopolymer from which a non-gummy, hygroscopic, flexible and pliable thin layer which can be deposited on an epidermal surface can be made and which optionally contains a plurality of plasticizers each having a different solvency power for 2-hydroxyethyl methacrylate homopolymer thereby controlling the pliability of the layer of 2-hydroxyethyl methacrylate homopolymer. On page 14 of Israel Patent No. 91422, it is indicated that the thin layer is formed when a cosmetic formulation is deposited on an epidermal surface. Although at pages 21-23 of the Israel patent, a cosmetic formulation of Dento-Med discloses a number of possible ingredients, there is no mention and no implication of the use of fragrances therein such as those fragrances which can diffuse out of the membrane as is claimed in our invention.
Blakeway and Sauvage, U.S. Pat. No. 5,369,092 issued on Nov. 29, 1994, discloses novel odorant compositions comprising panthenol with a perfume concentrate and ethanol, whereby the addition of panthenol prolongs the diffusion of perfume materials from the skin. The panthenol, however, is different in kind rather than degree from the polymers used in film forming the fragrance-containing films of our invention and does not give rise to the unexpected, unobvious and advantageous results of the fragrance carrier system of our invention; and further, does not give rise to the fragrance substance evolving from the film into the environment proximate the film by means of molecular diffusion at a permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-minute.
PCT Patent Application No. 97/25018 published on Jul. 17, 1997 and assigned to Launceston, Ltd. of St. Peter Port, Guernsey, Channel Islands, discloses a scented nail polish which comprises:
(a) at least one solvent;
(b) at least one resin;
(c) at least one colorant; and
(d) at least one liquid perfume
where the weight ratio of resin:liquid perfume is from 2.5:1 down to 1:2.5. Examples of the resin component of the scented nail polish of PCT Patent Application No. 97/25018 are nitrocellulose, cellulose acetate, cellulose acetate-butyrate, ethyl cellulose, vinyl polymers, methacrylate polymers and acrylate polymers. PCT Patent Application No. 97/25018 does not expressly or implicitly disclose the fragrance control release system of our invention, whereby a fragrance substance is evolved from a polymeric film into the environment proximate said film by means of molecular diffusion at a permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-minute in a sustained and controlled release manner as measured by the xe2x80x9cFRAGRANCE PERMEATION TESTxe2x80x9d described, infra.
Our invention is directed to an emulsifier-free, single phase, nonporous, continuous, permeable polymeric film having a substantially uniform thickness of from about 1 up to about 150 microns, having entrapped and dissolved therein molecules of at least one fragrance substance capable of evolving from said film into the environment proximate said film by means of molecular diffusion at a permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min in a sustained and controlled release manner.
More particularly, our invention is directed to a film which is an emulsifier-free, single phase, nonporous, continuous, permeable polymeric film which comprises a polymer and a fragrance substance located on the surface of a substantially planar solid or semi-solid support, e.g., the epidermis, said polymeric film having two substantially parallel laminar surfaces, a first laminar polymer surface and a second laminar polymer surface, said second laminar polymer surface being juxtaposed with at least a portion of said surface of said planar solid or semi-solid support, e.g., the epidermis, said polymeric film having a substantially uniform thickness of from about 1 micron up to about 150 microns, said polymeric film having entrapped and dissolved therein molecules of at least one fragrance substance in an initial weight ratio Ri of fragrance:polymer of from about 0.01:20 up to about 50:0.01, said fragrance substance being:
(i) capable of evolving from within the polymeric film through said first laminar polymer surface into the environment proximate to and above said first laminar polymer surface by means of substantially steady state molecular diffusion at a substantially constant permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min in a sustained and controlled release manner; and
(ii) substantially incapable of permeating that portion of said second laminar polymer surface which is juxtaposed with the surface of said planar solid or semi-solid support (e.g., the epidermis)
said polymeric film having two regions located across the cross-section of said polymeric film, taken along the directional vector from said first laminar polymer surface to said second laminar polymer surface:
(a) a first permeation region proximate and immediately adjacent to said first laminar polymer surface; and
(b) a second reservoir region proximate and immediately adjacent to said second laminar polymer surface,
said first permeation region being juxtaposed with said second reservoir region, said second reservoir region containing a high proportion of said fragrance substance relative to the proportion of said fragrance substance contained in said first permeation region.
Another embodiment of the article of our invention is a film which is an emulsifier-free single phase, nonporous, continuous, permeable polymeric-gel film comprising:
(i) a water-soluble or water-swellable polymer;
(ii) a fragrance material;
(iii) water; and
(iv) a gelling agent composition comprising at least one gelling agent,
said film being located on the surface of a substantially solid or semi-solid support, said polymeric-gel film having two substantially parallel laminar surfaces:
(i) a first laminar polymeric-gel surface; and
(ii) a second laminar polymeric-gel surface,
said second polymeric-gel surface being juxtaposed with at least a portion of said surface of said substantially planar solid or semi-solid support (e.g., the epidermis), said polymeric-gel film having a substantially uniform thickness of from about 1.0 microns up to about 150 microns, said polymeric-gel film having entrapped and dissolved therein:
(i) molecules of at least one fragrance substance in an initial weight ratio of fragrance:polymeric gel of from about 0.01:20 up to about 50:0.01; and
(ii) water molecules in an initial weight ratio of water:polymeric gel of from about 1:500 up to about 500:1,
said molecules of fragrance substance and said molecules of water being uniformly dispersed in a single phase throughout said polymeric-gel film, said fragrance substance being:
(a) capable of evolving from within the polymeric gel film through said first laminar polymeric-gel surface into the environment proximate said first laminar polymeric-gel surface by means of molecular diffusion at a permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min in a substantially controlled release manner in accordance with Fick""s second law; and
(b) substantially incapable of permeating that portion of said second laminar polymeric-gel surface which is juxtaposed with said surface of said planar solid or semi-solid support (e.g., the epidermis).
Our invention is also directed to a process for imparting a fragrance into the environment above the unobstructed outer surface of a polymer film coated on the surface of a solid or semi-solid support (e.g., the epidermis) comprising the sequential steps of:
(i) combining a composition comprising a solvent consisting of water, ethanol or mixtures of water and ethanol with a solvent-soluble polymer solute to form a polymer solution; then
(ii) dissolving a soluble fragrance substance in said polymer solution in order to form an aromatized polymer solution; and then
(iii) uniformly applying said aromatized polymer solution to said substantially planar surface of said solid or semi-solid support,
whereby molecules of the fragrance are capable of evolving from the resulting polymeric film into the environment surrounding the polymeric film by means of molecular diffusion at a permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min in a sustained and controlled release manner.
More specifically, the process of our invention for imparting a fragrance into the environment above the unobstructed outer surface of a polymer film coated on the surface of a solid or semi-solid support comprises the sequential steps of:
(i) dissolving a quantity of Q moles of solute polymer in V liters of solvent to form a polymer solution of concentration Q/V molar;
(ii) dissolving F moles of fragrance substance in said solution of polymer to form a fragrance solution of concentration of F/V molar;
(iii) uniformly applying said solution to said surface of said solid support,
whereby a single-phase, nonporous, continuous, permeable polymeric film having a thickness of from about 1 micron up to about 150 microns and having dissolved therein said fragrance substance capable of evolving from said film into the environment proximate to the unobstructed outer surface of said film by means of molecular diffusion of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min in a sustained and controlled release manner, wherein Q/V is in the range of from about 0.01 up to about 3 and F/V is in the range of from about 0.01 up to about 3.
Another process of our invention is one for imparting a fragrance into the environment proximate to the unobstructed outer substantially planar surface of a polymeric-gel film which is coated on the substantially planar surface of a solid or semi-solid support (e.g., the epidermis) comprising the steps of:
(i) dissolving a quantity of from about 0.01 up to about 20 parts by weight of a solvent-soluble polymer solute in from about 30 up to about 99.98 parts by weight of a solvent/base composition in order to form a polymer-base composition solution containing from about 0.01% up to about 67% polymer;
(ii) adding a gelling agent to the polymer-base composition solution in order to form a polymer-base solution-gelling agent composition;
(iii) dissolving from about 0.01 up to about 50 parts by weight of a soluble fragrance substance in said polymer-base solution-gelling agent composition in order to form an aromatized polymer-base solution-gelling agent composition; and
(iv) uniformly applying said aromatized polymer-base solution-gelling agent composition to said substantially planar surface of said solid or semi-solid support, whereby a single-phase, nonporous, continuous, permeable polymeric-gel film having a thickness of from about 1 micron up to about 150 microns, having dissolved therein molecules of said fragrance substance capable of evolving from said film into the environment proximate to the unobstructed outer surface of said film by means of molecular diffusion from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min in a sustained and controlled release manner is formed.
Preferably, the aforementioned process involves the steps of:
(i) dissolving the solvent-soluble polymer in a solvent such as water, ethanol or mixtures of water and ethanol;
(ii) mixing the resulting polymer solution with a base containing a substantial amount of propylene glycol and/or polypropylene glycol to form the polymer solution-base mixture;
(iii) feeding the resulting polymer solution-base mixture;
(iv) adding a gelling agent to the resulting mixture; and
(v) adding an aromatizing agent to the resulting mixture to form an aromatized polymer solution-base-gelling agent mixture.
Preferably, the solvent-polymer solute is in an amount of from about 30 up to about 99.98 parts by weight of the solvent/base composition, whereby a polymer-base composition solution is formed containing from about 0.01% up to about 67% polymer.
Preferred film forming polymers are as follows:
(i) LUVISKOL(copyright) VA 55E having the structure: 
xe2x80x83wherein n is an integer of from about 10 up to about 50 and m is an integer of from about 10 up to about 50;
(ii) ULTRAHOLD(copyright) 8 having the structure: 
xe2x80x83wherein each of x, y and z are integers in the range of from about 10 up to about 50;
(iii) LUVIQUAT(copyright) FC or LUVIQUAT(copyright) HM having the structure: 
xe2x80x83wherein each of x and y are integers in the range of from about 10 up to about 50;
(iv) ADVANTAGE PLUS(copyright) having the structure: 
xe2x80x83wherein each of x, y and z are integers in the range of from about 10 up to about 50;
(v) GAFQUAT(copyright) 734N or GAFQUAT(copyright) 755N (trademarks of International Chemical Specialties, Inc.) having the structure: 
xe2x80x83wherein m is an integer of from about 5 up to about 30;
(vi) DIAFORMERS(copyright) having the structure: 
xe2x80x83wherein each of m and n are integers of from about 10 up to about 40;
(vii) GAFQUAT(copyright) HS-100 having the structure: 
xe2x80x83wherein each of x and y are integers of from about 10 up to about 20 (a trademark of International Chemical Specialties, Inc.); and
(viii) OMNIREZ(copyright) 2000 and GANTREZ(copyright) A-425 having the structure: 
xe2x80x83wherein x is an integer of from about 5 up to about 30 (trademarks of International Chemical Specialties, Inc.).
In addition, another polymer group useful in the practice of our invention is partially hydrolyzed polyvinyl acetates, also termed xe2x80x9cpolyvinyl alcoholxe2x80x9d with polyvinyl acetate as hydrolyzed to an extent of from about 73% up to about 99%. Such material is prepared by means of any of Examples I-XIV of U.S. Pat. No. 5,051,222 issued on Sep. 24, 1991, the specification for which is incorporated by reference herein.
Thus, the polyvinyl alcohol or the partially hydrolyzed polyvinyl acetate is prepared first by polymerizing (via a xe2x80x9cfree radicalxe2x80x9d polymerization mechanism) polyvinyl acetate having the formula: 
according to the reaction: 
thereby forming a polyvinyl acetate wherein x+y are such that the number average molecular weight of the final product is between 5,000 and 67,000. The resulting polyvinyl acetate having the formula: 
is then hydrolyzed first to form a partially hydrolyzed polyvinyl acetate according to the reaction; 
or a mixture of polyvinyl alcohol and partially hydrolyzed polyvinyl acetate according to the reaction: 
If desired, the partially hydrolyzed polyvinyl acetate may be further hydrolyzed to form polyvinyl alcohol with very few acetyl groups present (thereby forming, for example, 99% hydrolyzed polyvinyl acetate) according to the reaction: 
In any event, the ratio of acetyl moieties to hydroxyl moieties is less than about 1:3 in the structure: 
and x and y are defined whereby x+y gives rise to a polymer that has a number average molecular weight of between about 5,000 and 67,000.
Various grades of partially hydrolyzed and substantially fully hydrolyzed forms of hydrolyzed polyvinyl acetate can be used in the practice of our invention, to wit:
As stated, supra, the fragrance material or mixture of materials useful in the practice of our invention are those which permeate the polymer film at rates equal to or lower than 1.0 mg/cm2/minute as determined by the xe2x80x9cFRAGRANCE PERMEATION TEST,xe2x80x9d described in detail in Example I, infra.
The fragrance substance useful in the practice of our invention has a maximum vapor pressure of about 4.1 mm/Hg at 30xc2x0 C. When the fragrance material has topnote components, middle note components and bottom note components, the vapor pressure ranges for each of these three groups of components should be as follows:
(a) with respect to the bottom note components, the vapor pressure range should be from about 0.0001 mm/Hg up to about 0.009 mm/Hg at 25xc2x0 C.;
(b) with respect to the middle note components, the vapor pressure range of the middle note components should be from 0.01 mm/Hg up to 0.09 mm/Hg at 25xc2x0 C.; and
(c) with respect to the top note components, the vapor pressure range of the top note components should be from 0.1 mm/Hg up to 2.0 mm/Hg at 25xc2x0 C.
An example of such a fragrance as described, supra, is as follows:
In general, the perfume materials useful in the practice of our invention have a calculated log10P of between 1 and 8 (P being the n-octanol-water partition coefficient of the perfumery material).
The range of permeation rates of the perfumery materials through the polymer film or the gel film is from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-min (milligram-millimeter/square centimeter-minute). The following materials having the following calculated log10P also have the following permeation rates through various polymer films useful in the practice of our invention:
The mathematical models for the fragrance release are as follows:                               ⅆ          M                          ⅆ          t                    =              2        ⁢                                            D              e                                      π              ⁢                              xe2x80x83                            ⁢                              t                e                                                    ⁢                              A            ge                    ⁡                      [                                                            c                  e                  i                                ⁡                                  (                  t                  )                                            -                                                c                  e                                ⁡                                  (                  t                  )                                                      ]                                ;                                ⅆ                                    c              e                        ⁡                          (              t              )                                                ⅆ          t                    =                                                  h              D                        ⁢            A                                V            e                          ⁡                  [                                                                      c                  g                                ⁡                                  (                  t                  )                                                            K                ge                                      -                                          c                e                            ⁡                              (                t                )                                              ]                      ;                                ⅆ          M                          ⅆ          t                    =                                    -                          v              e                                ⁢                                    ⅆ                                                c                  e                                ⁡                                  (                  t                  )                                                                    ⅆ              t                                      =                              v            g                    ⁢                                    ⅆ                                                c                  g                                ⁡                                  (                  t                  )                                                                    ⅆ              t                                            ;                                c          g                ⁡                  (          t          )                    =                                    v            e                                v            g                          ⁡                  [                                                    c                e                            ⁡                              (                0                )                                      -                                          c                e                            ⁡                              (                t                )                                              ]                      ;                                ⅆ                                    c              e                        ⁡                          (              t              )                                                ⅆ          t                    =              α        ⁡                  [                      β            -                                                            c                  e                                ⁡                                  (                  t                  )                                            ⁢              γ                                ]                      ;          xe2x80x83        ⁢          α      =                                    h            D                    ⁢                      A            ge                                    v          e                      ;              β      =              ϵ        ⁢                  xe2x80x83                ⁢                              c            e                    ⁡                      (            0            )                                ;          xe2x80x83        ⁢          γ      =              [                  1          +          ϵ                ]              ;          xe2x80x83        ⁢          ϵ      =                        v          e                                      v            g                    ⁢                      K            ge                                ;                                c          e                ⁡                  (          t          )                    =                                                  c              e                        ⁡                          (              0              )                                            (                          1              +              ϵ                        )                          ⁢                  {                      ϵ            +                          exp              ⁡                              [                                                      -                    α                                    ⁢                                      xe2x80x83                                    ⁢                  γ                  ⁢                                      xe2x80x83                                    ⁢                  t                                ]                                              }                      ;                                c          g                ⁡                  (          t          )                    =                                                  K              ge                        ⁢                                          c                e                            ⁡                              (                0                )                                                          (                          1              +                              1                /                ϵ                                      )                          ⁡                  [                      1            -                          exp              ⁡                              (                                                      -                    α                                    ⁢                                      xe2x80x83                                    ⁢                  γ                  ⁢                                      xe2x80x83                                    ⁢                  t                                )                                              ]                      ;                      c        g            ⁢              (        t        )              =                                        K            ge                    ⁢                                    c              e                        ⁡                          (              0              )                                                (                                                                      K                  ge                                ⁢                                  v                  g                                                            v                e                                      +            1                    )                    [                                                  (                              1                -                                  exp                  ⁢                                      {                                                                  -                                                  (                                                      1                            +                                                                                          v                                e                                                                                                                              K                                  ge                                                                ⁢                                                                  v                                  g                                                                                                                                              )                                                                    ⁢                                                                                                    h                            D                                                    ⁢                                                      A                            ge                                                                                                    v                          e                                                                    ⁢                      t                                        }                                                                        ]                    ;                      
                    ⁢                                                    c                g                            ⁡                              (                ∞                )                                      =                                                            K                  ge                                ⁢                                                      c                    e                                    ⁡                                      (                    0                    )                                                                              (                                                                                                    K                        ge                                            ⁢                                              v                        g                                                                                    v                      e                                                        +                  1                                )                                              ;                      xe2x80x83                    ⁢                                    and              ⁢                              
                            ⁢                                                                    c                    g                                    ⁡                                      (                    t                    )                                                                                        c                    g                                    ⁡                                      (                    ∞                    )                                                                        =                          [                              1                -                                  exp                  ⁢                                      {                                                                  -                                                  (                                                      1                            +                                                                                          v                                e                                                                                                                              K                                  ge                                                                ⁢                                                                  v                                  g                                                                                                                                              )                                                                    ⁢                                                                                                    h                            D                                                    ⁢                                                      A                            ge                                                                                                    v                          g                                                                    ⁢                      t                                        }                                                              ]                                      ,            ⁢              xe2x80x83            
wherein each of the terms set forth in the foregoing mathematical models are set forth in the paper entitled xe2x80x9cMathematical Models of Flavor Release from Liquid Emulsionsxe2x80x9d by Harrison, et al, JOURNAL OF FOOD SCIENCE, July/August 1997, Volume 62, No. 4, at pages 653-664, the disclosure of which is incorporated by reference herein. The controlling factors for xe2x80x9cflavorsxe2x80x9d as set forth in the Harrison, et al paper apply equally as well to the fragrances discussed herein.
Examples of gels useful in the practice of our invention are as follows:
(i) sodium stearate;
(ii) bis(ureido) gels as disclosed in Freemantle in the article xe2x80x9cDurable Organic Gelsxe2x80x9d appearing in CHEMICAL and ENGINEERING NEWS, Volume 76, No. 4, at pages; 35-38, the disclosure of which is incorporated by reference herein.
(iii) soap, fatty acid-based gelling agents as particularly described in U.S. Pat. No. 5,585,092 issued on Dec. 17, 1996 (Trandai, et al), the specification for which is incorporated by reference herein, including salts of fatty acids containing 12 to about 40 carbon atoms, preferably salts of C12-C22 fatty acids, more preferably salts of C14-C20 fatty acids and most preferably salts of C16-C20 fatty acids with the salt forming cations for use in these gelling agents including metal salts such as alkalai metals, for example, sodium and potassium and alkaline earth metals, for example, magnesium and aluminum; and in addition, hydrogel-forming polymeric gelling agents as disclosed in U.S. Pat. No. 4,076,663 (Masuda, et al) issued on Feb. 28, 1978, the specification is incorporated by reference herein; and U.S. Pat. No. 4,731,067 (Le-Khac) issued on Mar. 15, 1988, incorporated by reference herein in its entirety. The suitable hydrogel-forming polymeric gelling agents are specifically discussed at columns 6-12 of U.S. Pat. No. 5,585,092 (Trandai, et al) issued on Dec. 17, 1996, incorporated by reference herein in its entirety; and
(iv) silicone gels having the structures: 
as described in detail in U.S. Pat. No. 5,623,017 issued on Apr. 22, 1997, the disclosure of which is incorporated by reference herein.
When that embodiment of our invention is used wherein the fragrance is evolved from a gel coating, the gel coating formulation as stated, supra, preferably contains propylene glycol or polypropylene glycol with the number of propylene oxy units being from about 2 up to about 30. An example of the formulation useful with the gel is as follows:
water;
propylene glycol;
aluminum chlorohydrate;
dimethicone;
sorbitol;
cyclomethicone;
dimethicone copolyol;
ethyl alcohol; and
fragrance.
Preferably, the fragrance materials of our invention have a log10P of between about 1 up to about 5.
The barrier properties of an effective film forming polymer are, to a good approximation, a function of the degree of crystallinity of the film and the solubility of the fragrance ingredient in the film. Polyvinyl alcohol, for example, has a high degree of crystallinity and has good barrier properties to a large number of fragrance ingredients. Hydroxypropyl cellulose, on the other hand, forms an amorphous film and, thus, its barrier properties are a function of the solubility of the fragrance ingredient in the hydroxypropyl cellulose. The solubility of fragrance ingredients in amorphous films can estimated by the calculated octanol-water partition coefficient for the fragrance ingredient. For amorphous hydrophilic films such as the film formed using hydroxypropyl cellulose, fragrance ingredients having a calculated octanol-water partition coefficient of 3 or less readily permeate this film (the calculated 1-octanol/water partition coefficient (xe2x80x9cclogPxe2x80x9d) is calculated according to the technique of J. T. Chou and C. J. Jurs, Chem. Inf. Comput. Sci., 19, 3, 172-178 (1979)).
For the practice of our invention in personal care products such as perfumes, colognes, aftershave splashes, lotions, underarm deodorant and antiperspirant products such as sticks, roll-ons, aerosols and creams; hair products such as styling gels, sprays and mousses and home care products such as liquid surface cleaners and waxes, the product contains preferably from about 1 up to about 3% of a nontoxic alcohol such as ethyl alcohol and/or water, a water soluble film forming polymer and from about 0.1 up to about 30% by weight of a fragrance that has been found not to permeate the film formed by this polymer to any great extent; that is, having a permeation value of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-minute.
Upon application of the product to a solid or semi-solid surface, e.g., the epidermis, the volatile solvent in most cases ethyl alcohol and/or water evaporates, leaving a film of polymer on the surface of the skin which contains entrapped fragrance. The fragrance permeates out of the polymer at a rate that is proportional to its permeation through the polymer as determined by the xe2x80x9cFRAGRANCE PERMEATION TEST,xe2x80x9d set forth and specifically described in Example I, infra. Fragrance elements that permeate slowly through the film forming polymer will permeate slowly out of the polymer layer applied to the surface. On the other hand, fragrances that permeate rapidly through the polymer will not be retained by the polymer that has been deposited on the surface of the skin, for example.
The advantages of using the fragrance controlled release systems of our invention, described herein are:
(1) an enhanced sensory impression of the fragrance due to the increased duration of its release from the surface of the skin, for example;
(2) an enhanced sensory impression of freshness and vibrance due to the increased duration of fragrance ingredients that make up the topnotes of the fragrance; and
(3) triggered release of the fragrance from water soluble polymer films upon the addition of moisture.
For the practice of our invention in personal care products such as perfumes, colognes, aftershave splashes, lotions, underarm deodorant and antiperspirant products such as sticks, roll-ons, aerosols and creams; hair care products such as stylizing gels, sprays and mousses and home care products such as liquid surface cleaners and waxes, the product of our invention contains from 1-3% of an alcohol and/or water soluble film forming polymer and from 0.1 up to about 30% of a fragrance that has been found not to permeate the film formed by this polymer (that is, a low permeation rate of from about 1xc3x9710xe2x88x927 up to about 0.1 mg-mm/cm2-minute in a substantially controlled release manner in accordance with Fick""s Second Law, to wit:             ∂      C              ∂      θ        =            ∑              i        =        1            n        ⁢          xe2x80x83        ⁢                  -                  D          i                    ⁢                                    ∂            2                    ⁢                      C            i                                    ∂                      x            2                              
wherein Di is the diffusivity of the ith fragrance substance component; n is the number of fragrance substance components; x is the distance of travel of the ith fragrance component within the polymer film to the first laminar polymer surface thereof; xcex8 is time; and Ci is the concentration in gram moles per liter of the ith component of said fragrance substance.
Upon application of the product, the volatile solvent, in most cases ethyl alcohol and/or water and/or mixtures of ethyl alcohol and water, evaporates, leaving a film of polymer on the surface which contains entrapped fragrance. The fragrance permeates out of the polymer through the first laminar polymer surface or laminar polymer-gel surface at a rate that is proportional to its permeation through the polymer as determined by the xe2x80x9cFRAGRANCE PERMEATION TEST,xe2x80x9d described in detail in Example I, infra. Fragrance elements that permeate slowly through the film forming polymer will permeate slowly out of the polymer layer applied to the surface. On the other hand, fragrances that permeate rapidly through the polymer will not be retained by the polymer that has been deposited on the surface.
In carrying out the aforementioned process, it is helpful in blending the fragrance, film forming polymer and solvent to use a homogenizer and/or a rotor/stator high shear mixer. Examples of a homogenizer useful in the practice of this aspect of our invention are laboratory homogenizer models 15MR and 31MR manufactured by APV Gaulin, Inc. of 44 Garden Street, Everett, Mass. 02149. Examples of rotor/stator high shear mixers are the high shear in-line mixers manufactured by Silverson Machines, Inc., P.O. Box 589, 355 Chestnut Street, East Long Meadow, Mass. 01028 and by the Scott Process Equipment Corporation, P.O. Box 619, Sparta, N.J. 07871. The aforementioned homogenizers and rotor/stator high shear mixers can be used in conjunction with one another, with the rotor/stator high shear mixers being used first, and then in order to complete the blending, the resultant emulsion is further homogenized using the homogenizers such as laboratory homogenizers, models 15MR and 31MR.
The details of the aforementioned homogenizers and rotor/stator high shear mixers are set forth in the xe2x80x9cDETAILED DESCRIPTION OF THE DRAWINGSxe2x80x9d section, infra, in the description of FIGS. 3C, 3D and 3E.
Our invention is also directed to apparatus for carrying out the aforementioned processes for imparting a fragrance into the environment above the unobstructed outer surface of a polymer film coated on the surface of a solid or semi-solid support or a polymeric-gel film coated on the substantially planar surface of a solid or semi-solid support such as the epidermis. Such apparatus comprises:
(i) mixing means for a composition comprising a solvent selected from the group consisting of water, ethanol and mixtures of water and ethanol (e.g., 50:50 mixtures) with a solvent-soluble polymer solute to form a polymer solution;
(ii) downstream from said mixing means, blending means for dissolving a soluble fragrance substance in said polymer solution in order to form an aromatized polymer solution (for example, the homogenizer and/or rotor/stator high shear mixer, briefly described, supra, and described in the description of FIGS. 3C, 3D and 3E, infra);
(iii) downstream from said blending means, coating means for uniformly applying said aromatized polymer solution to said substantially planar surface of said solid or said semi-solid support; and, optionally,
(iv) downstream from said coating means, drying means for drying the coated polymer solution on said solid or said semi-solid support.
The coating means of (iii) may be any applicator device well known to those having ordinary skill in the art. The drying means, useful in the practice of our invention, can be any portable or stationary drying apparatus, such as that manufactured by the CONAR(copyright) Corporation.